Convertible roofs offer protection from inclement weather and enjoyment of activities in the open during suitable weather. More particularly, convertible roofs may be stored or erected for selectively covering an area, or exposing the area to ambient weather conditions. During suitable weather conditions, some activities are more enjoyable in the open. Further, some sports require natural turf and satisfactory cultivation of large turf areas generally requires open exposure.
However, severe weather conditions render some activities unacceptable for the activity and/or for the observers. For instance, soccer requires natural turf; but under some conditions the game destroys the turf and discourages the fans. Baseball games are "called" due to rain, at great expense in enthusiasm and money. Swimming pools are delightful when used in warm sunny weather but impossible in cold, windy conditions. Ice rinks are delightful in mild cold but impossible in extreme cold or in warm weather. Many other activities can be imagined where a convertible roof is desirable for selectively retracting and extending the roof in response to different weather conditions. Past convertible roofs have been complex, mechanical, expensive, unreliable, hazardous in earthquake conditions, visibly invasive even when retracted, and not accepted for many reasons.
Attempts to develop convertible roofs using fabrics and pneumatics are disclosed in prior patents. For example U.S. Pat. No. 4,833,837 to Bonneau discloses a folding radome for use in sports, scientific, military or industrial applications. The radome includes a flexible roof having two hemispherical halves. In this roof system, inflated panels are supported by structural arches. The panels are stretched into place by mechanical winch systems. Complex mechanics and expensive permanent structure visually obstructs the area the roof covers, even when the roof retracts.
U.S. Pat. No. 3,332,176 to Knetzer discloses an inflatable structure that forms a hemispherical dome using guidance and support from internal bracing. Lune-shaped cells are interconnected pneumatically by valves that transfer inflation from cell to cell as scheduled pressure differentials are reached. Complex valving and internal supports limit the applications for which the disclosed structure may be used. For example, the internal support bracing precludes safe and smooth convertible action of the structure over an occupied space. Additionally, the valving reduces the rate of closing and opening of the structure below acceptable limits for many uses.
U.S. Pat. No. 4,317,315 to LeBlang discloses a shelter having two halves. Inflatable ribs form a structure for a flexible skin. The two halves are erected separately with high pressure in the structural tubes laced together to form a portable, tent-like structure. The system does not lend itself to being convertible over a large area or while the area is occupied.
The present invention accordingly provides an improved solution for a convertible roof.